Abstract
INTRODUCTION AND OBJECTIVES
Although it is considered that SpCs in the bladder modulate bladder functions such as a compliance correction, there are limited data to investigate the differences of SpCs with variation of region. The purpose of this study was to investigate the pharmacological characteristics of SpCs in mucosal layer by differentiating them from other components and to clear their roles on bladder function.
METHODS
The urinary bladder of male guinea pigs was opened longitudinally. The mucosa and detrusor muscle layers were divided by microscope-guided dissection. Three types of tissue strip were prepared; mucosal, detrusor and intact strips. Preparations were superfused with Tyrodes of solution for 90 minutes. Baseline SpCs was recorded for 10 minutes; followed by superfusion with agonists for a further 30 minutes. Area-under-the-curve (AUC) of SpCs and tonic contractions were differentiated by computer software. Following functional experiments, some strips were stained with HE and Masson′s trichrome to estimate the percentage of muscle. Images were digitised and analysed using ImageJ.
RESULTS
Mucosal strips contained much less muscle (4.5%) than detrusor (73.6%) or intact (63.2%). AUC of baseline SpCs in intact, detrusor and mucosal strips were 10.5, 0.94, 4.5 mN*mm-2*sec, respectively (mucosa vs detrusor, p<0.001). Drugs effect; SpCs in mucosal strips were suppressed by 30 µM capsaicin (26.3%), though SpCs in detrusor strips were increased (246%). 1µM αβmATP (P2X1) increased AUC in detrusor (270%) and intact strips (344%) but was suppressed in mucosal strips (66%). Among ADP (P2Y1), UTP (P2Y2,4) and UDP (P2Y6), only UDP increased SpCs in intact strips. By changing pH to 5.5, SpCs in detrusor and intact strips were suppressed. Immediately after returning pH to 7.4, a large, transient contraction was generated. A similar, but reduced pattern was observed in mucosal strips.
CONCLUSIONS
The mucosal strips generated greater baseline SpCs than in the detrusor. It was unlikely that the mucosal SpCs were due to residual muscle because the amount of muscle was much less than detrusor strips. Mucosal and detrusor SpCs had different pharmacological profiles thus it was proposed that different cellular components generate SpCs. The enhanced SpCs from intact strips suggest an interaction between mucosa and detrusor layers. Based on the results, the bladder wall has fine mechanisms to regulate SpCs so as to keep bladder tone and compliance. Disorders of SpCs seem to generate disturbances of bladder.
Although it is considered that SpCs in the bladder modulate bladder functions such as a compliance correction, there are limited data to investigate the differences of SpCs with variation of region. The purpose of this study was to investigate the pharmacological characteristics of SpCs in mucosal layer by differentiating them from other components and to clear their roles on bladder function.
METHODS
The urinary bladder of male guinea pigs was opened longitudinally. The mucosa and detrusor muscle layers were divided by microscope-guided dissection. Three types of tissue strip were prepared; mucosal, detrusor and intact strips. Preparations were superfused with Tyrodes of solution for 90 minutes. Baseline SpCs was recorded for 10 minutes; followed by superfusion with agonists for a further 30 minutes. Area-under-the-curve (AUC) of SpCs and tonic contractions were differentiated by computer software. Following functional experiments, some strips were stained with HE and Masson′s trichrome to estimate the percentage of muscle. Images were digitised and analysed using ImageJ.
RESULTS
Mucosal strips contained much less muscle (4.5%) than detrusor (73.6%) or intact (63.2%). AUC of baseline SpCs in intact, detrusor and mucosal strips were 10.5, 0.94, 4.5 mN*mm-2*sec, respectively (mucosa vs detrusor, p<0.001). Drugs effect; SpCs in mucosal strips were suppressed by 30 µM capsaicin (26.3%), though SpCs in detrusor strips were increased (246%). 1µM αβmATP (P2X1) increased AUC in detrusor (270%) and intact strips (344%) but was suppressed in mucosal strips (66%). Among ADP (P2Y1), UTP (P2Y2,4) and UDP (P2Y6), only UDP increased SpCs in intact strips. By changing pH to 5.5, SpCs in detrusor and intact strips were suppressed. Immediately after returning pH to 7.4, a large, transient contraction was generated. A similar, but reduced pattern was observed in mucosal strips.
CONCLUSIONS
The mucosal strips generated greater baseline SpCs than in the detrusor. It was unlikely that the mucosal SpCs were due to residual muscle because the amount of muscle was much less than detrusor strips. Mucosal and detrusor SpCs had different pharmacological profiles thus it was proposed that different cellular components generate SpCs. The enhanced SpCs from intact strips suggest an interaction between mucosa and detrusor layers. Based on the results, the bladder wall has fine mechanisms to regulate SpCs so as to keep bladder tone and compliance. Disorders of SpCs seem to generate disturbances of bladder.
| Original language | English |
|---|---|
| Pages (from-to) | e44 |
| Number of pages | 1 |
| Journal | Journal of Urology |
| Volume | 191 |
| Issue number | 4S |
| DOIs | |
| Publication status | Published - 1 Apr 2014 |
| Externally published | Yes |